1. Field of the Invention
This invention relates to key operated switches for keyboards, more particularly it relates to key operated switches having printed circuit conductors and contacts.
Key operated switches are needed in a plurality of equipments, as separate parts, or assembled as a keyboard. Electronic typewriters and data processing equipments especially require such keyboards in large quantities. Consequently, such keyboards should not only be inexpensive to manufacture but at the same time should be reliable in operation at a very high speed and be protected from accumulation of dirt.
2. Description of Related Art
A relatively simple key operated switch is disclosed in DE No. 30 36 336 C2. There a spring is described which has three tongues, two of which serve as a return spring for the key and one as contact spring. This arrangement permits an especially flat construction combined with the required deep depression of the keys. With this known key it is possible to obtain a durable reliably working keyboard, but due to its construction largely automated manufacture is not possible making it relatively expensive.
Known foil keyboards, e.g., as disclosed in DE No. 31 22 517 A1, are too expensive per se and, as is generally known, they have the disadvantage of a reduced contact cycle number, whereby switch life is very limited.